Typically a large number of semiconductor devices are formed on wafers. The semiconductor devices are formed by repeating a number of basic operations on a wafer. The basic operations include layering, patterning, doping, and heat processing. The final semiconductor formed has many layers of material and includes as many as 10,000 or more individual transistors. Rather than make each semiconductor device individually, a number of devices are formed on a single wafer. The entire wafer is subjected to the basic operations discussed above in order to form hundreds of semiconductor chips or devices. Typically, after the semiconductor devices are formed, the semiconductor devices are tested and sorted. Next, the wafer is sliced and diced so that each individual semiconductor device is separated from the others formed on the wafer.
The individual semiconductor devices are formed on fragile material. As a result, the individual semiconductor devices are packaged, in part for physical protection. Packaging also dissipates the heat from the semiconductor and provides leads between the individual chip or die and an exterior portion of the package. The leads allow for electrical connection between the chip or die and a printed circuit board or other device.
There are many different types of packages. One common package is a flip chip which has a series of bumps or balls or leads formed in an array on a surface of the flip chip. The flip chip is attached to a substrate during packaging. The flip chip includes an inner layer dielectric (ILD) where the devices associated with the flip chip are formed. One method of packaging includes attaching the flip chip or die to the substrate and then encapsulating the flip chip or die in plastic or epoxy. Part of this packaging method includes a molded underfill (MUF) where the plastic or epoxy is forced into the gap between the flip chip and the substrate. A high clamping force is placed on top of the flip chip or die and a high transfer pressure is applied during the MUF process. The ILD is a fragile, thin film layer. The high clamping force and the high transfer pressure causes the ILD to crack during the MUF process. Cracks in the ILD result in failures of the flip chip. In some instances, these failures may be latent failures which manifest themselves only after manufacture. Of course part failures are never desirable.
The description set out herein illustrates the various embodiments of the invention and such description is not intended to be construed as limiting in any manner.